1. Field of the Invention
The present invention relates to an optical recording medium, and more particularly to an optical recording medium comprising a substrate, and a recording layer formed thereon, which recording layer is composed of (a) a first recording layer which comprises a light-absorbing organic compound and can be deformed upon irradiation of light thereto, and (b) a second recording layer which comprises a sulfide containing antimony in an amount of 50 atm % or more, and can be deformed in accordance with the deformation of the first recording layer, whereby optical recording can be performed.
2. Discussion of Background
Conventionally, an overwrite type of optical recording medium has been developed and used in practice, which comprises a substrate and a light-reflecting-and-absorbing dye-containing recording layer formed thereon, in which optical recording is carried out by applying a laser beam to the recording layer so that the illuminated section of the recording layer is removed, causing the formation of holes or indentations in the recording layer, as described in a text titled "Organic recording materials for optical disks" by "Abe", published by Bushin Shuppan Co., Ltd. in Japan.
In order to prevent foreign material in the air from adhering to the recording layer, the structure used in this type of recording medium is a so-called sandwich structure, which utilizes a pair of transparent substrates, each provided with a recording layer, or a pair of substrates, each comprising a protective substrate provided with a recording layer, joined together through an air space so that the recording layer is on the inside.
This type of conventional optical recording medium which uses a dye with light reflecting and light absorbing capabilities in the recording layer and records as the result of the formation of holes or indentations from the application of light, has the drawback that the recording sensitivity takes a large drop in the case where a protective layer is provided in close contact with the recording layer, because a change in shape occurs in the holes and indentations during recording.
In addition, even in the case where a protective layer is not provided, a great deal of recording laser power is required, in particular, to record at high speed and high density. If the recording laser power is low, a sufficient change in reflectance is not obtained.
Also, when the hole or indentation is formed, part of the recording layer which is removed is scattered as decomposed or melted material onto the surface of the other part of the recording film. The adherence of this material to the surface causes noise and errors to develop.